Linked Life Data

17227420

Source:http://linkedlifedata.com/resource/pubmed/id/17227420

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2007-1-17
pubmed:abstractText
Cyanobacteria are regarded as the main N(2)-fixing organisms in marine waters. However, recent clone libraries from various oceans show a wide distribution of the dinitrogenase reductase gene (nifH) originating from heterotrophic bacterioplankton. We isolated heterotrophic N(2)-fixing bacteria from Baltic Sea bacterioplankton using low-nitrogen plates and semi-solid diazotroph medium (SSDM) tubes. Isolates were analysed for the nitrogenase (nifH) gene and active N(2) fixation by nested polymerase chain reaction (PCR) and acetylene reduction respectively. A primer-probe set targeting the nifH gene from a gamma-proteobacterial isolate, 97% 16S rDNA similarity to Pseudomonas stutzeri, was designed for measuring in situ dynamics using quantitative real-time PCR. This nifH gene sequence was detected at two of 11 stations in a Baltic Proper transect at abundances of 3 x 10(4) and 0.8 x 10(3) copies per litre seawater respectively. Oxygen requirements of isolates were examined by cultivation in SSDM tubes where oxygen gradients were determined with microelectrodes. Growth, and thereby N(2) fixation, was observed as horizontal bands formed at oxygen levels of 0-6% air saturation. The apparent microaerophilic or facultative anaerobic nature of the isolates explains why the SSDM approach is the most appropriate isolation method. Our study illustrates how combined isolation, functional analyses and in situ quantification yielded insights into the oxygen requirements of heterotrophic N(2)-fixing bacterioplankton isolates, which were confirmed to be present in situ.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
1462-2912
pubmed:author
pubmed:issnType
Print
pubmed:volume
9
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
152-64
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Isolation and gene quantification of heterotrophic N2-fixing bacterioplankton in the Baltic Sea.
pubmed:affiliation
Department of Biology and Environmental Science, Kalmar University, S-391 82 Kalmar, Sweden.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't